The overall objectives of this research are an understanding of the control and organization of the eukaryotic genome and the physiological (adaptive) significance of genetic variation at both the structural and control gene levels. Specifically, the long-term objectives of this research are an understanding of the control and organization of the amylase system of Drosophila pseudoobscura and the physiological significance of the genetic variability observed in the system. The amylase system consists of the structural gene Amy plus associated control genes which regulate Amy's expression. Three separate projects are involved in this research. First, at the structural gene level, purified amylases will be biochemically characterized to establish biochemical differences on which selection could act - i.e., differences that may be physiologically significant. Second, selection experiments based on the observed biochemical differences will be conducted. Third, at the regulatory level, control genes which regulate Amy expression will be characterized in terms of their genetics, variability, associations, physiological significance and other properties. Two types of control genes will be studied, regulatory genes which control amylase synthesis, activity or turnover and temporal genes which control Amy expression in space and time. To conduct these studies a combination of biochemical, genetic, population genetic and developmental methods will be used. An amylase activity assay method will be used to study the regulatory genes and characterize the purified amylases. A tissue specific staining procedure will be used to study larval temporal genes. The significance of this research is that it addresses one of the major questions of population genetics, the genetic basis of adaption, and that it utilizes a well integrated, holistic approach for doing so.